Develop Reference

Cut region out of Bitmap with Path

I'm trying to get cut a jigsaw puzzle piece out of an image, creating a new Bitmap image. I'm using a Path object to do this. This is the current result.
And how I achived this
Path path = new Path();
// Multiple path methods to create shape of puzzle piece...
path.close();
Bitmap source = BitmapFactory.decodeResource(getResources(), R.drawable.flowers);
Bitmap workingCopy = source.copy(Bitmap.Config.ARGB_8888, true);
Canvas canvas = new Canvas(workingCopy);
path.setFillType(Path.FillType.INVERSE_WINDING);
Paint paint = new Paint();
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
canvas.drawPath(path, paint);
((ImageView) findViewById(R.id.myImage)).setImageBitmap(workingCopy);
I wish I could have it transparent instead of black and cut out everything outside the bounds of path.

I've tried it using a PNG-file with transparancy, and the background is transparent in stead of black.

Android how to apply mask on ImageView?

So I tried the code from here: Creating an ImageView with a mask. I'm using the following images as original and mask:
However, the result I get is this:
Note that the window background is not black, but holo light (which on the galaxy nexus looks like a very pale gray, not completely white). The second image is the result I get when an item is selected on a list view.
If instead I create a new Bitmap using the same algorithm and then pass it to the image view instead of overriding onDraw(), it draws correctly:
Canvas canvas = new Canvas();
Bitmap mainImage = //get original image
Bitmap maskImage = //get mask image
Bitmap result = Bitmap.createBitmap(mainImage.getWidth(), mainImage.getHeight(), Bitmap.Config.ARGB_8888);
canvas.setBitmap(result);
Paint paint = new Paint();
paint.setFilterBitmap(false);
canvas.drawBitmap(mainImage, 0, 0, paint);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
canvas.drawBitmap(maskImage, 0, 0, paint);
paint.setXfermode(null);
imageView.setImageBitmap(result);
I get the expected result:
Note the fade is correctly applied. This is more evident when a selection is made.
So what's going on on ImageView's onDraw method to create this black backdrop instead of letting the window background show through? What's interesting is that if the original image itself has some transparency, that transparency is respected, for example:
I can't figure it out by myself. I'd rather be able to do it on onDraw instead of pre-creating the bitmap because it only works for bitmaps as source and mask. I want to be able to do it with other drawables like gradients and solid colours but on those cases the width and height are not set.

I have found the perfect combination for creating masking without black border after researching through all the stackoverflow posts. It suits my purpose quite well.
Currently I'm creating a draggable view using one normal image and a masking image (a png with transparency), so I'll need to override the onDraw function.
private Bitmap mImage = ...;
private Bitmap mMask = ...; // png mask with transparency
private int mPosX = 0;
private int mPosY = 0;
private final Paint maskPaint;
private final Paint imagePaint;
public CustomView (final Context context) {
maskPaint = new Paint();
maskPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
imagePaint = new Paint();
imagePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OVER));
}
/* TODO
if you have more constructors, make sure you initialize maskPaint and imagePaint
Declaring these as final means that all your constructors have to initialize them.
Failure to do so = your code won't compile.
*/
#Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
canvas.drawBitmap(mMask, 0, 0, maskPaint);
canvas.drawBitmap(mImage, mPosX, mPosY, imagePaint);
canvas.restore();
}

Answering my own question. The Xfermode was working as intended. The paint was making the resulting are of the canvas transparent (which was the canvas used by the window activity). Since the canvas itself was being set transparent, the window was showing what was behind it: the black background.
To do it properly, indeed a new Bitmap has to be created to hold the result of the alpha mask. I updated the code to take into account drawables of all types.

In this Code Apply:
mask_over = BitmapFactory.decodeResource(
getResources(), mask_over1[0]);
icon = Bitmap.createScaledBitmap(icon, screenwidth, screenwidth, false);
mask_over = Bitmap.createScaledBitmap(mask_over, screenwidth, screenwidth, false);
back_img=createBitmap_ScriptIntrinsicBlur(Bitmap.createScaledBitmap(cropview.croppedImage, screenwidth, screenwidth, false),25.0f);
LinearLayout.LayoutParams layoutParams111 = new LinearLayout.LayoutParams(screenwidth, screenwidth);

how to set additive overlay of jpg images to achieve transparency

I need to overlay two images in live wallpaper. The overlay images is the jpg which needs to be set to "additive" overlay. it adds the pixel value rather than calculating the transparency. how can i achieve this in android ?

You can make use of Android's Bitmap and Drawable classes mixed with Canvas, and try something like in this snippet:
public static Drawable mergeImage(Drawable orig, Drawable over, int left, int top) {
Bitmap original = ((BitmapDrawable)orig).getBitmap();
Bitmap overlay = ((BitmapDrawable)over).getBitmap();
Bitmap result = Bitmap.createBitmap(original.getWidth(), original.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(result);
Paint paint = new Paint();
paint.setAntiAlias(true);
canvas.drawBitmap(original, 0, 0, paint);
canvas.drawBitmap(overlay, left, top, paint);
return new BitmapDrawable(result);
}
I've coded a photo image gridview overlayered with "online status" using the above lines. Hope that it works for you too.

A more general approach may be to create a PorterDuffXfermode with your wanted PorterDuffMode and then set it on the Paint object that you use with your canvas, as referenced in mthama's answer but substituting some lines. This allows you to use other Porter-Duff modes as wanted/needed.
Paint paint = new Paint();
paint.setAntiAlias(true);
canvas.drawBitmap(original, 0, 0, paint);
paint.setXferMode(new PorterDuffXferMode(PorterDuff.Mode.OVERLAY));
canvas.drawBitmap(overlay, left, top, paint);
Mind you, I haven't tried this, so go with mthama's answer. :)

Combine image and text to drawable

I want to create a drawable, which consists of a map pin(bubble) and some text. The bubble should be in the background and the text in the foreground.
This drawable should be passed in super(drawable) of the class BalloonItemizedOverlay which extends ItemizedOverlay<Item>.
In other words, I want to show text in the bubble that appears in the map.
I am using the Hello Mapview tutorial

This method takes a drawable from your resources, draws some text on top of it and returns the new drawable. All you need to do is give it the resource id of your bubble, and the text you want on top. Then you can pass the returned drawable wherever you want it.
public BitmapDrawable writeOnDrawable(int drawableId, String text){
Bitmap bm = BitmapFactory.decodeResource(getResources(), drawableId).copy(Bitmap.Config.ARGB_8888, true);
Paint paint = new Paint();
paint.setStyle(Style.FILL);
paint.setColor(Color.BLACK);
paint.setTextSize(20);
Canvas canvas = new Canvas(bm);
canvas.drawText(text, 0, bm.getHeight()/2, paint);
return new BitmapDrawable(bm);
}
To preserve density you need this constructor
BitmapDrawable (Resources res, Bitmap bitmap)
So, keeping your context, last return should be something like
return new BitmapDrawable(context.getResources(), bm);
This prevent an undesired resized drawable.

Autofit text in a rectangle on android

I'm using a view and drawing over a bitmap some text,it does not have a fixed size, so I want the text to fit the rectangle I define and if it's needed split the string in some lines.
I don't know how to do it in android.
I found one solution using StaticLayout, but doesn't work.
Here is my code:
Bitmap arBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ar_bitmap);
canvas.drawBitmap(arBitmap ,bitmapPos,20, null);ll);
Paint paint = new Paint();
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.WHITE);
canvas.drawText(textToDisplay,textPos , 35, paint);
Thanks